Front-back printer

ABSTRACT

A printer has continuously moving type character bearing elements moving along a print line on one side of a document. Type hammers located on the opposite side of the document are operable to impact the document and a type ribbon or the like with selected ones of the type characters which are themselves selectively advanced towards the hammers by an associated actuating means.

[451 May 29, 1973 United States Patent [191 Dayger et al.

Pecchenino l 1/1965 Wasserman [54] FRONT-BACK PRINTER Brown et al..

hh gg .m.m nn nnt uun CCP wfim 99 0 WNW 6 6mm 3 ,1. 4 2 2M4 333 n I m n 0 mM r m m 3,416,442 12/1968 [73] Assignee: International 7 Business Machines 3,4 5, 70 9/|969 Belson er a], Corporation, Armonk, N.Y. 3,498,216 3/l970 Kaiser et aL.

Dec. 28, 1970 Appl. No.: 101,736

[22] Filed:

Primary Examiner-William B. Penn Attorney-Hanifin & Jancin and Francis V. Giolma 101/93 C ABSTRACT ....B41j 9/10 A printer has continuously moving type character ...l0l/93 C, 111 bearing elements moving along a print line on one side of a document. Type hammers located on the opposite [56] References Cited side of the document are operable to impact the document and a type ribbon or the like with selected ones UNITED STATES PATENTS 3 /1956 Crawford........

of the type characters which are themselves selectively 101/93 C advanced towards the hammers by an associated ac- ....l01/93 C tuating means.

I 10 Claims, 7 Drawing Figures 2,737,883 2,792,779 5/1957 Toeppen et al. 2,993,437 7/1961 Demer et al PAIEN IED HAYES I975 sum 1 or g FIG. 3

INVENTORS T T T T T T T T T CONTROLS V! E N E M R L n AG A E A E N DRO E D MM NHWH wwo x B 9 1 m FIG. 4

FRONT-BACK PRINTER DESCRIPTION OF PRIOR ART I-Ieretofore, train/chain printers have either used print hammers to impact a document and ribbon against type characters as they pass a print position such as inthe Cunningham U.S. Pat. No. 3,241,480, which issued Mar. 22, 1966, or have used print hammers to impact pivoted type character bearing elements against a ribbon and document which are backed up by a solid platen as in the Cunningham U.S. Pat. No. 3,451,335, which issued on June 24, 1969.

SUMMARY OF THE INVENTION Generally stated, it is an object of this invention to provide a new and novel arrangement or printers.

More specifically, it is an object of this invention to provide a printer in which selected print hammers impact a document against selected character bearing type elements which, as they move past the selected positions, are advanced from a normal rest position toward the document. 7

Another object of this invention is to combine the best features of a back printer with the best features of a front printer to minimize shadow printing.

Yet another object of this invention is to provide a front-back printer with control means for activating oppositely disposed type character bearing elements and type hammers in selected print positions.

Still another object of this invention is to provide in a printer for having a plurality of print hammers and a plurality of selectively actuatable type character bearing elements which are advanced in predetermined timed relation with operation of selected print harnmers for impacting a document therebetween.

It is also an object of this invention to provide for using selectively movable type'character bearing elements and print hammers on opposite sides of a document for printing thereon.

Yet another important object of this invention is to provide for simultaneously operating selected print hammers on one side of the document and selected type character bearing elements on the other side of the document for printing thereon.

It is an important object of this invention to provide in a printer for simultaneously energizing a selected print hammer and actuating means for advancing a selected type character bearing element towards said print hammer while said type character bearing element is at the print hammer position.

Another important object of this invention is to provide in a printer for selectively advancing one of two adjacent type character bearing elements as it passes one of two print positions which are provided with a single double width print hammer.

Still another object of this invention is to provide for selectively advancing a group of type character bearing elements during passage by selected spaced apart print positions on one side of a document, and actuating selected print hammers on the other side of the document covering said spaced apart print positions.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawing.

DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a partial schematic view in perspective of a printer mechanism embodying the invention in one of its forms.

FIG. 2 is a schematic partly-sectioned view in side elevation of the printer mechanism of FIG. ll.

FIG. 3 is a schematic circuit diagram showing one arrangement for energizing the print hammers and type element actuators of FIGS. 1 and 2.

FIG. 4 is a schematic plan view of the type character bearing elements, actuators, and print hammers of FIGS. 1 and 2.

FIG. 5 is a partial schematic plan view of a printer mechanism embodying the invention in another form.

FIG. 6 is a partial schematic view in front elevation of the cam and subscan selector bars as used in FIG. 5, and

FIG. 7 is a schematic showing of the type character bearing elements and double width print hammers such as may be used in the printer mechanism of FIG. 5 together with a partial table showing typical availability of characters for printingduring different ones of the scans.

DESCRIPTION OF A PREFERRED EMBODIMENT FIG. 1 shows a printer apparatus of one type with which the present invention may be used, and comprises a Type Cartridge 10, a portion of which is shown as having a Base Plate 12 with a Raised or Rail Portion 12a, upon which a plurality of individual type carries represented by the Type Carrier 11 move along a continuous path for'printing on a Document 13. A portion of the path of the Type Carriers 11 includes a straight portion along which printing can occur and which is hereinafter referred to as the print line. Each Type C arrier 11 has one or more Pivotal Type Levers or type character bearing Elements 11a with different engraved Type Characters 110 disposed on the surface thereof adjacent the print line. Full sequences of Type Characters 11c are obtained by assembling a plurality of Type Carriers 11 in predetermined arrangements on the Base Plate 12. The Type Carriers 11 are driven preferably in the form of a train along the Rail 12a on the Base Plate 12 so that they travel at a constant velocity and are maintained in abutting relation with each other along the straight portion of the path of travel.

The printer apparatus of FIG. 1 is somewhat similar to the back printer which is described in US. Pat. No. 3,224,366, which issued on Dec. 21, 1965, to J. M. Cunningham, and-in accordance with the well-known operational principles thereof, the Paper Document or Form 13 is positioned behind an Ink Ribbon 14 of the like. A plurality of Print Hammers 24 arelocated on the other side of the Document or FOrm 13 from the Type Levers 11a and as shown in FIG. 2, are each disposed to be actuated by means of an associated Electromagnet 26 having an Armature 28 pivotally mounted and operably connected to the Print Hammer 24 by means of a Push Rod 30. The Electromagnet 26 is provided with an Operating Winding 27 for attracting the Armature 28 to actuate the Print Hammer 24 by means of the Push Rod 30.

Instead of having these Print Hammers 24 impact the Document 13 and Ribbon 14 against stationary type characters on the Type Carrier 11 as in the Cunningham patent, it will be noted that the Type Characters 110 are mounted on Pivotal Levers 11a on the Type Carrier 11, being mounted on a common Pivot 11b in a manner such as shown in the Cunningham US. Pat. No. 3,451,335, which issued on June 24, 1969. As shown in FIGS. 1 and 2, the Type Levers 1 la are disposed to be advanced as they pass selected print positions by Actuating Means 31 comprising a series of Slides or Actuator Bars 32 slidably mounted by means of a Housing 33, and biased toward the right to an advanced position by means of Spring 34, to engage different ones of the Type Levers 11a as they pass by. and cam them into an advanced position, which is toward the right from the normal rest position as shown. The Actuators 32 are generally T-shaped and have a vertical Head Portion 32a comprising an armature which is disposed to be held in an attracted position by means of a C-shaped Electromagnet 35 against the bias of the Spring 34. The plurality of Electromagnets 35 have a common Hold Winding 36 linking the Electromagnets 35 for holding the Actuators 32 in the retracted position, and are individually provided with Buck Windings 37, which may be selectively energized to oppose the Hold Winding 36 and to release their respective Armatures 320, thus permitting the Spring 34 to advance the associated Actuator 32 for camming a selected Type Lever into the operated position.

Referring to FIG. 3, it will be seen that the Hold Winding 36 may be continuously energized from a suitable source of electrical energy while the Buck Windings 37 may be individually connected by means such as a suitable Driver 38 to a suitable Control 40 similar to that described in the Demer et al. U.S. Pat. No. 2,993,437, which issued July 25, 1961, for selectively pulsing both the Buck Winding 37 and the corresponding Winding 27 of the associated Electromagnet 26.

Printing is achieved in the following manner. A properly timed pulse is applied from the Controls 40 through the selected Driver 38 and applied to the two Coils 27 and 37, which are connected in parallel. The Buck Out Winding 37 being pulsed allows the Armature 32a of the associated Actuator 32 to be release from its Hold Magnet 35. The Actuator 32 is driven toward the Type Lever 11a through the action of the Spring 34. The slide motion causes a preselected Type Lever 11a to be advanced or forced out of alignment with the adjacent type levers, for about 0.005 inch, for example, as it passes the advanced Slide 32, where it remains while the associated Print Hammer 24 is being propelled towards the Paper 13 through the action of the same pulse being applied to the Print Magnet 27. The Hammer 24 forces the Paper 13 and the Ribbon 14 against the Type Character 110 on the selected Type Lever 11a which is projecting beyond the adjacent levers, as shown in FIG. 4, causing printing of the particular Type Character 11c on the Type Lever 11a. The extended or advanced Type Lever 11a prevents the Paper 13 from being forced against the adjacent nonadvanced Type Levers lla, thus preventing printing (shadow) of the adjacent characters even though they are very closely spaced. The pulse applied to the Windings 27 and 38 is turned off by the Controls 40 just prior to the time the Print Magnet Armature 28 seals '1 and Ribbon 14 that causes the Slide or Actuator 32 to be restored to the Hold Magnet 35. If desired, a cam surface could be provided on the back of the Type Lever 11a similar to that described in the co-pending application of John E. Drejza, Ser. No. 887,203, entitled Anti-Nipping Device for Printers, filed Dec. 22, 1969. This type of cam would be used to restore all the Slides 32 on those occasions where power might be turned off. A magnet operated bail (not shown) which operates at power ON could also be used for this purpose. A restore device is only necessary when a nowork type magnet as shown is used. If a work type magnet is used, the restore problem does not exist. It can be seen that since the potential for interference between the Type Lever lla and Hammer 24 is a maximum of 0.005 inch, the timing to prevent nipping of the type is much less critical with the present invention than for a normal front printer 0.0l60.0l8 inch interference for a six-part form (even greater with thicker forms). The 0.005 inch remains constant regardless of the number of copies. It should be pointed out that since the Slide or Actuator 32 is only required to move the small distance of about 0.007 inch (0.002 inch extra is included to be sure that it does not normally rub the type) in the same time that the Hammer 24 is moving about 0.115 inch, the required velocity of the Slide 32 is low, and thus a low velocity impact occurs at the slide/type interface, preventing wear due to the impact. The Hammers 24 and Type Levers 11a shown in FIG. 4 have widths on the order of 0.100 inch and 0.075 inch, respectively, but other relations can be as easily used. While only one Type Carrier 11 has been shown in FIGS. 1 and 2, it will be realized that a plurality are used in abutting relation and the Controls 40 are arranged to scan a plurality of Print Hammers 24 either in succession or in a plurality of subscans, so that only every second, third hammer, etc. is optioned to print in sequence as described in the Demer et al. patent.

The hammer blocking or shadow is improved over that of normal back printers because the Type 11c comes out to the Paper 13 while in back printers the hammer has to deflect the Paper 13 between the guides to get at the type. The contact time between the Slide 32 and the Hammer 24 is less than that of hammer, type and platen used in normal front printing, assuming the initial hammer velocities (energy) are equal. Past studies have shown the contact time is minimized by increased hammer velocity and reduced hammer mass for a given energy. In the case of the Hammer 24 and Slide 32, the mass of the print hammer and its velocity are the controlling factors. In the case of the front printer, it is generally the (lower) velocity of the type and hammer combination and their (greater) combined mass.

This mechanism also lends itself very well to lower speed and lower cost machines. This can be accomplished by using different arrangements and omitting one-half, three-quarters, one-third, etc. of the Print Magnets 26 and changing the Hammer 24 configuration to cover the two or more columns, correspondingly. The results achieved are the same as those I achieved with an incrementing hammer unit. In this case, however, it is not necessary to do any incrementing. It is only necessary to use double width or some other such width combination of hammers. This is possible because only the characters selected for each scanning will be extended to the print positions, thus permitting selection of either of two or more type characters opposite such multiple width hammers. Of course, it will be necessary to provide a Slide or Actuator 32 and a Driver 38 for each position. However, a Driver 38 required to operate only the Slide 32 would be much lower in cost since it does not have to do so much work.

Referring to FIGS. 5 and 6, there is shown a different embodiment of the invention for advancing the plurality of Type Levers 1 1a out of the print line so that printing can take place with closely spaced Type Levers 11a without shadow printing of the adjacent characters. This mechanism is simpler than the one already described, but it is required to operate much more frequently. As shown, three Subscan Actuators or Bars 50, 52 and 54 are provided for advancing selected Type Levers 11a along the print line. The Subscan Bars 50, 52 and 54 extend the length of the print line and are provided with projecting Cam Portions 50a, 50b and 5c spaced, by way of example, opposite every third Print Hammer 24 for engaging and advancing Type Levers Ila at these locations, being, for example, located opposite the first, fourth, seventh and tenth print hammers, etc. The Subscan Bar 52 has corresponding Projections 52a, 52b, 52c, etc. positioned opposite the second, fifth, eighth and 11th Print Hammers 24 for engaging and advancing Type Levers 11a at those positions, while the Subscan Bar 54 has corresponding Cam Projections 54a, 54b and 540, etc. positioned in line with the third, sixth, ninth and 12th etc. Print Hammers along the print line. The Subscan Bars or Actuators 50, 52 and 54 are provided with arms at both ends similar to the Arms 50A, 52A and 54A carrying Cam Follower Rollers 50B, 52B and 54B designed to be operated by means of a rotating Cam 55 having a plurality of Detents or Raised Cam Surfaces 56 around the periphery, spaced to advance the Subscan Bar 50 every time a Type Lever Ila passes the first Print Hammer 24, for example. The Subscan Bars 52 and 54 are advanced each time a Type Lever 11a passes the second and third Print Hammer, respectively. The Cam 55 may be driven by means of the Cartridge Drive Gear 58, which is provided with teeth engaging with corresponding teeth on the rear portions of the Type Carriers 11 for moving the Type Carriers 11 past the print line in the manner described in the Cunningham patent hereinbefore referred to.

In this embodiment of the invention the operation is as follows: each of the three Subscan Bars 50, 52 and 54 is associated with one of three different subscans that establish the firing order of the Print Hammers 24 (in Print Scan 1, Subscan Bar 50 is cammed forward so that Hammers l, 4, 7, 10, etc. are optioned to fire; in Print Subscan 2, Subscan Bar 52 is cammed forward and Hammers 2,5,8, etc., are optioned to fire; and in Print Subscan 3, Subscan Bar 54 is cammed forward so that Print Hammers 24-3, 24-6, 24-9, etc. are optioned to fire). Each of the three Subscan Bars 50, 52 and 54 has a series of Cam Projections or Teeth 50a, 50b, 50c, etc.; 52a, 52b, 520, etc.; and 54a, 54b, 540, etc., which are so located that the teeth line up opposite the Print Hammers 24, which can be optioned to fire in that particular Subscan. Because the Subscan Bars 50, 52 and 54 only push out those Type Levers 6 those characters remains retracted and cannot create shadow printing. The determination of which Print Hammers 24 are actually fired during any subscan is determined by compare means (not shown) which determines whether the particular character opposite a Print Hammer is the one it is desired to print at that position, as described in the Demer et al. patent.

As shown in FIG. 7, the arrangement of FIG. 5 can also be used with Print Hammers 24', etc., similar to the Hammers 24, but which are two print positions wide, with Type Levers 11a having the same arrangement with the Subscan Bars 50, 52 and 54, as shown in FIG. 5. As shown by the partial table in FIG. 7, in the first subscan, which is the first of the A sequence, an A could be printed by the left side of the first Hammer 24' in Position 1, the followed by a I in Position 7, and a Q in Position 13 and a Y in Position 19, etc., through Scan 144. On the second scan of the A sequence, an F could be printed in Position 5, an N in Position 11, and a V in Position 17. The third subscan could produce a C in Position 3, a K in Position 9, and an S in Position 15, etc., and so on through 144 scans for the A Scan Sequence. This is followed by the B Scan Sequence of Scans 145 through 288 with the characters shown in the rectangles, for example A, I, Q and Y in the 145th scan being printed by the right side of the Print Hammers 24 in the second, eighth, 14th and 20th positions, and the other characters shown being optioned to be printed in the corresponding positions.

From the above description and the accompanying drawing it will be seen that the described mechanism has a higher speed capability than a normal front printer because the hammer timing conditions are much less critical. It does not have the type and hammer wear exposure inherent in a front printer because there are no high velocity metal-to-metal impacts. It has capabilities for printing more copies than a front printer since the hammer timing is not a function of paper thickness. It has good paper handling capabilities because it does not require a small type to hammer gap or throat. Hammer blocking or shadow on the last copy of a multiple form is minimized. Hammer contact time is reduced, resulting in reduced slurring. This device also has the capability of allowing the economics (reduction in the number of magnets) of a lower speed incrementing hammer unit printer without actually requiring the hammers to increment.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in formand details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. In a printer, a plurality of type carriers movable past a plurality of print positions along a print line on one side of and adjacent to a document and having a portion of each carrier bearing a type character thereon movable relative to said type carrier in a direction substantially perpendicular to said print line and toward said document from a normal position which is a predetermined distance from said document,

a plurality of print hammers positioned along said print line on the other side of said document having operating means for actuating said print hammers to impact said document against said type characters for printing on said document, actuating means operable to engage said movable portions of said type carrier to move said type character bearing portions toward said document, and

circuit means connected to said print hammer operating means and said type character bearing portion actuating means to effect substantially simultaneous operation of selected ones of said actuating means to move said type characters toward said document from one side and said print hammer operating means to cause said print hammers to impact said document from said other side, so as to impact said document between said type characters and said type hammers.

2. The invention as defined in claim 1 characterized by each of said type carriers having a plurality of said movable character bearing portions comprising pivoted lever portions mounted thereon and movable toward said document and each bearing a type character adjacent the free end thereof.

3. The invention as defined in claim 2 characterized by said operating means for said print hammer and actuating means for said type carrier bearing portion comprising electromagnetic means having operating windings connected in parallel circuit relation to be energized simultaneously from a common source of electrical energy.

4. The invention as defined in claim 3 characterized by said type character bearing portion actuating means comprising a no-work electromagnet with an armature biased to operate said type bearing portion and a magnetic core member with means for generating a magnetic flux therein to hold said armature away from said type bearing portion and a buck winding on said core member disposed to be energized to reduce the holding effect of said magnetic flux and permit said biasing means to move said armature toward said type bearing portion.

5. The invention as defined in claim 1 characterized by said means operable to move said pivoted type character bearing portion comprising a bar slidably disposed in each print position, connected to the armature of said no-work electromagnet and operable to engage a selected type character bearing portion.

6. The invention as defined in claim 5 characterized by each said print hammer having an operating face spanning multiple print positions.

7. The invention as defined in claim 5 characterized by said type characters having a pitch different than that of said print positions so that alignment of a type character with a print position occurs only at spaced intervals.

8. The invention as defined in claim 1 characterized by said means operable to advance said type character portion comprises a plurality of bars movable toward and away from said document and having cam surface projections for engaging different ones of said type character portions at spaced apart intervals greater than the spacing between adjacent type character portions.

9. The invention as defined in claim 8 characterized by cam means connected in driving relation with said type carriers operable to cause said bars to advance selected groups of said type character bearing portions in timed relation to the passage of said portions past different print positions.

10. The invention as defined in claim 9 characterized by there being a plurality of said bars for sequentially advancing different groups of said spaced apart type character bearing portions. 

1. In a printer, a plurality of type carriers movable past a plurality of print positions along a print line on one side of and adjacent to a document and having a portion of each carrier bearing a type character thereon movable relative to said type carrier in a direction substantially perpendicular to said print line and toward said document from a normal position which is a predetermined distance from said document, a plurality of print hammers positioned along said print line on the other side of said document having operating means for actuating said print hammers to impact said document against said type characters for printing on said document, actuating means operable to engage said movable portions of said type carrier to move said type character bearing portions toward said document, and circuit means connected to said print hammer operating means and said type character bearing portion actuating means to effect substantially simultaneous operation of selected ones of said actuating means to move said type characters toward said document from one side and said print hammer operating means to cause said print hammers to impact said document from said other side, so as to impact said document between said type characters and said type hammers.
 2. The invention as defined in claim 1 characterized by each of said type carriers having a plurality of said movable character bearing portions comprising pivoted lever portions mounted thereon and movable toward said document and each bearing a type character adjacent the free end thereof.
 3. The invention as defined in claim 2 characterized by said operating means for said print hammer and actuating means for said type carrier bearing portion comprising electromagnetic means having operating windings connected in paralleL circuit relation to be energized simultaneously from a common source of electrical energy.
 4. The invention as defined in claim 3 characterized by said type character bearing portion actuating means comprising a no-work electromagnet with an armature biased to operate said type bearing portion and a magnetic core member with means for generating a magnetic flux therein to hold said armature away from said type bearing portion and a buck winding on said core member disposed to be energized to reduce the holding effect of said magnetic flux and permit said biasing means to move said armature toward said type bearing portion.
 5. The invention as defined in claim 1 characterized by said means operable to move said pivoted type character bearing portion comprising a bar slidably disposed in each print position, connected to the armature of said no-work electromagnet and operable to engage a selected type character bearing portion.
 6. The invention as defined in claim 5 characterized by each said print hammer having an operating face spanning multiple print positions.
 7. The invention as defined in claim 5 characterized by said type characters having a pitch different than that of said print positions so that alignment of a type character with a print position occurs only at spaced intervals.
 8. The invention as defined in claim 1 characterized by said means operable to advance said type character portion comprises a plurality of bars movable toward and away from said document and having cam surface projections for engaging different ones of said type character portions at spaced apart intervals greater than the spacing between adjacent type character portions.
 9. The invention as defined in claim 8 characterized by cam means connected in driving relation with said type carriers operable to cause said bars to advance selected groups of said type character bearing portions in timed relation to the passage of said portions past different print positions.
 10. The invention as defined in claim 9 characterized by there being a plurality of said bars for sequentially advancing different groups of said spaced apart type character bearing portions. 